Liquid crystal displays ("LCD's"), in which the electro-optically active element comprises liquid crystalline material, are well known in the art.
One type of LCD employs an encapsulated liquid crystal structure in which a liquid crystal composition is encapsulated or dispersed in a containment medium such as a polymer. When a voltage corresponding to a sufficiently strong electric field is applied across the encapsulated liquid crystal structure (the "field-on" condition), the alignment of the liquid crystal molecules therein is re-oriented in accordance with the field, so that incident light is transmitted. Conversely, in the absence of such a voltage (the "field-off" ) the alignment of the liquid crystal molecules is random and/or influenced by the liquid crystal-matrix interface, so that the structure scatters and/or absorbs incident light. The applied voltage at which the structure changes from its field-off condition to its field-on condition is generally referred to as the operating voltage.
Choice of the containment medium and liquid material can effect LCD performance. in aspects such as threshold voltage, switching speed, and hysteresis. Some of the effects are bulk effects, while others arise from interactions at the containment medium-liquid crystal composition interface.
An important performance parameter is the opening voltage at which the display switches from one visual state to the other. A lower voltage means lower power requirements, making the display attractive for battery-powered devices. Other important performance parameters are switching speed and hysteresis. We have discovered additives and other improvements which markedly reduce the operating field, the switching speed, and/or the hysteresis in a display comprising encapsulated liquid crystal structures.